SIMULTANEOUS DETERMINATION OF PENICILLINS AND SULFONAMIDES IN MILK BYHIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple and rapid method for the simultaneous determination of three penicillinase resistant penicillin derivatives (cloxacillin, dicloxaci llin and nafcillin) and two sulfonamides (sulfamonomethoxine and sulfa dimethoxine) in milk by high performance liquid chromatography (HPLC) was developed. The samples were prepared by extraction with acetonitri le followed by liquid-liquid partition with n-hexane for clean up. The extracts were analyzed by HPLC utilizing a UV detector with a timer w hich changed the wavelength of detection at a programmed time. The sep aration was achieved on TSK gel ODS-80T(M) (4.6 X 150 mm i.d.) using a cetonitrile:0.05 M NaH2PO4 (31:69) as a mobile phase. Recoveries of dr ugs from fortified milk at the levels of 0.1 and 0.5 mug/ml were 77.3 approximately 82.1% and 88.2 approximately 91.7%, respectively. The de tection limit in 4-step time program measurement was 0.02 mug/ml for e ach drug.